Extant is a mystery thriller about a female astronaut (Berry) who tries to reconnect with her family after spending a year in outer space. Steven Spielberg is an executive producer on the show. As previously announced, Camryn Manheim will play Sam Barton, the best friend and closest confidante of Berry's main character, Molly.

After logging nine seasons as Dr. Luka Kovac on the NBC medical drama, Visnjic has appeared in multi-episode arcs on Leverage, Pan AmandRed Widow. O'Neill is also known for his roles on The West Wing and, most recently, Rectify.